Vulcanizing rubber with propynyl sulfenamides



Un ted StatesPatent ur sn zu e RUBBER mm PRQPXNYL SULFENAMIDES John I,DAmico, Nitro, W. Va., assignor to Monsanto C emica Q m1mny, S-.L0uis;M0-, a co por t on 9t Delaware ;No Drawings Filed Sept. 2, 1958,Ser. No. 758,513 12 Glaims. (Cl. "260-795) flfhe present inyentionrelates to the vulcanization of rubber employing as rators las .q nechemcal products. The accelerators may be described broadly asthiazolesulfenamides and can be schematically represented by the generaformula 7 EXAMPLE 1-PRODUCT A IN-isqpropybN-(Z-propynyl)-2-benzothiagglesulfenqmide A solution of thesodium salt of Z-mercaptobenzothh azole was prepared by dissolving 43parts (0.25 mole) of 97% mercaptobenzothiazole in 50 parts of watercontaining 40 parts (0.25 mole) of 25% sodium hydroxide solution. Thesolution preferably is filtered to remove any insoluble particlestherefrom. Thereupon 97.2parts (1.0- mole) ofN-isopropyl-Z-propynylamine were added over a P6I'i95 nttim whil a i n te m x u e Whe ll Of the ai l ne had be n add d 60 p t of 2 s f i s d reslow y ed wi h r n un or a mixtur es lted Next 22- pa t -3 n19' e) o omhypochlorite contained in 150' parts of water were added Slowly h emainta ni g t .t, t p w eofv t ma between 25-30" C. by suitable coolingmeans as re quired. Agitation was continued for about an hour after allthe hypochlorite had been added. Then 2 parts of sodium sulfite wereadded to remove any unreacted oxidizing agent from the reaction. Thereaction mixture was then extracted with a suitable solvent, such asether, in which any lay-product dior polysulfide are insoluble, theextract was filtered and the'ether solution washed with water toneutrality of the water washings. The extract was then dried by means ofanhydrous sodium sulfate to remove any water droplets present and theether was then removed in vacno at a temperature below 30 C. Asemi-solid which was dark amber in color was obtained in 54.8% yield.The product was soluble n .aee one. et er benzene ela ereiexm etha olethy cetate and heptane. Ihe expected rodu t of e pirical oxmula Q1sJina$a Qwefirmesl by na ysis. or itr gen n ntw eh howed 1. 1% present am:pared with 10.67% required for the formula shown.

- 2 EXAMPLE 2PRODUCT B5-chl0ro-N-isopr0pyl-N-(Z-propynyl)-2-benzofhiaz0iesulfenamideProceeding in the manner as described 1 1 except that 50.4 parts of5-chloromercaptobenzothiazole in 100 parts of water were usedin place ofthe mercaptoenzethiaze e theree ployes and-t eat n the produc theredescribed, a tan colored solid product, MLP. 4 34 5 (3., was obtained in54% yield which possessed the same characteristics in solvents'as theproduct of Example 1. Identification of the product of this example wasconfirmed by analysis as possessing the formula sHis a z as is evidentfrom the results that follow;

Percent Percent I Found Theory nitr 7 9. 9. ol'xlorlue 12. Al 11.425

parts (-1.25 mole) of ;N-isopropyl-2;propynylarnine were I slowly addedwith thorough -agitationwhereiipon 59: 3amof 25%- sulfuric acid wereadded over a period offti me and then 22.5 parts of sodium hypochloritesolution (9,3 mole as -a l6.1% solution) were slowly added while tainingthe temperature of the migtturebetw'een 255-80? 1 C, Agitationwasjcontinued tor "about-"an hour aiter'alij the reactants had beenadded. Thereupon, .4 parts sodium sulfite were added to destroy anyresidual oxidiz? ing agent present. After cooling to a miieimpmtennierait tre of 25 C, the mass, was extracted with ether, the. etherealsolution filtered, washed withwater to neutrality, dried and the solventremoved as described in Example '1. An amber colored oil was obtained in69.5% yield." product was soluble under the sameeondi tions as wasProduct A. Ide'ntification of the p rol at" s fii wNz z n as named in ths e amine can? firmed by analysis which produced asresu 'lercenti v t sm EXAMPLE def-ROD sulfer'pamide eaction te pe ature a ..0 .Cmthe e wasobtained a eam co ored 15. 119 me t n at 20.91." 1. a t r erystal zat pnfrom e h l a coho t s ispl ye theaams ma cteristiqs i sh eats min ed outn th three pre infl r'.

examples. The product was identified as the one named Patented June "28,

. 49%. yield. The expected product, of empiricalformula inthis. exampleby analysis, confirming the formula Mixes were prepared in the wellknown manner accord- C H N OS as is shown from the results: ing to. therecipes shown below:

Percent Percent Found Theory Stock A B C nitro en 9.17 9. 14 Parts byweight sulfur- 20. 70 20. 93

' Smoked sheets rubber Carbon black (Philblack O) V Zinc oxide EXAMPLE5.-PRODUCT E Stearic acid N b IN 2 l) 2 b I] I If d slgtifuratedhydrocarbon softener -tert. u r0 n enzo zzazo eszt enaml e urty p py yN,N-Dinitroso-diphenyl-p-phenylenediamino Again proceeding as describedin Example 3 hereof, g but using 97% mercaptobenzothiazole in place ofthe ig fii 4-lnethyl mercaptobenzothiazole and using 111.2 parts (1.0mole) of N-tert. butyl-Z-propynylamine instead of theN-isopropyl-Z-propynylamine in that example and The stocks so compoundedwere cured in the usual maintaining the reaction temperature at 45-50C., there manner by heating in a press for different periods of wasobtainedaviscous amber oil. The product, of empiri- 2 time at 144 C. Thephysical properties of the vulcal formula C H N S was confirmed byanalysis as is canizates are set forth below:

evident from the results that follow:

TABLE I Percent Percent Found Theory Tattoo Stick StIoSck Stack 7 Curenitro en 9. 86 10. 14 83 Modulus of Elasticity in lbs/111. at 1,9301,120

300% elongation -2--'- 45 2, 470 2, 490 2,160 I .6 a i338 EXAMPLE 6PRODUCT F Tensile atbreakiulbs/in. 45 21% 2:780 5:546N-cyclohexyl-N-(Z-propynyl) -2-benz0thlaz0le- Mooney scorch at 135 0.,mlns. for E sulfenamide 10 pomt rise above mlninlum value. 28 22.8 136.6

'I'his e xample, prepared as in Example 3 above, em-

ployed 99.8% mercaptobenzothiazole and N-cyclohexyl- 2-propynylaminc.The reaction temperature was'maintained at 50 C. and a semi-solidv wasobtained in Pardv comprising:

As further examplesof the invention mixes were pro;

C A-1 N 8 wasconfirmed by analysis for nitrogen con I St D tent whichshowed 9.00% present as compared with. 40 06 v 1 E F 9.26% requiredforthe formula shown. 7

, Further examples of the new compounds'comprise Parts by weightN-methyl-N-(Z-propynyl) 2 benzothiazolesulfenamide, j Nethyl-N-(Z-propynyl)-2-benzothiazolesulfenamide, N-Eltifiifillitiliiiiihrer::::::::::::::::::::::: 28 28 28 isobutyl-N-( 2propynyl -2-benzothiazolesulfenamide, N- gi {maefi g g gisoamyl-N-(Z-propynyl)-2-benzothiazolesulfenamide, N- sa iil rftgg ndwnnrbnn softener 3' a 3 benzyl-N-Z-(propynyl)2;benzothiazolesulfenamide and 3 59; d t frg N-allyl-N (2 propynyl) 2benzothiazolesulfenamide. Proiiilct ii 0.5 Most of the intermediatesrequired have been described 5 g? and others may be prepared byapplication of known printo not ciples. For example, N-isopropyl-Z-propynylamine may I be PrePaIed as T a Stirred solution n nStock E contained 6-dodecyl-1,2-dihydro-2,2,4-trimethyl- 591 gr 1110168)0f P PYl a 400 quinoline and Stock F contained phenyl-beta-naphthylfWater, 5 moles 0f -P PY added drop 5 amine as the antioxidant. Thestocks so compounded wise at 47..65. C. over a three hour period. Thestirred were cured in the usual manner by heatingfin a press reactionmixture was heated at 6070 C. for four hours. f difi' t e i f time atThe physical f cooling (1,500 grams of aqueous properties of'thevulcanizates are set 'forth below: sodlumhydroxlde was added over a tenminute period.

The reaction mixture was stirred for one additional hour 17 I TABLE IIand the sodium halide was removed by filtration. The top organic layerwas-dried over caustic andexcess iso- Time stock Stock Stock propylammewas removed by distillation. The distilla- D E F tlon of the residuethrough a 4-foot Vigreux-type column um gaveN-isopropyl-Z-propynylamine, B.P. 110-l11 C.

d i 1 N 1.4230, analyzlng 14.54% nltrogen as compared to 2 i ii 14.42%calculated for C H N. Boiling points of other g8 j g? g'ggg i gg typicalamines apparently not heretofore reported are: Tensile at break inlbs/in. 45 31740 41050 41110 t 60 3,540 a, 700 3,090N-allyl-2-propynylamme 123 C. at 760 mm. Moone scorch at 135 (3., mins.for N46. buty1 2 propynylamine 1214290 C. at 760 mm 10 point rise abovemlnlnlnm value. l1. 8 1t). 8 13 N-cyclohexyl-2-propynylamine 98100 C. at30 mm.

The products of the present invention as described Anothercharacteristic test was carried out in which herembefore have been foundeifective as accelerators of Product A was tested in a typical treadstock comprising the vulcanization of rubber as shown by the following100 parts of smoked sheet rubber, 50 parts of carbon examples whicharetypical of the class of products. 76 black (Philblack 0), 5 parts ofzinc oxide, 3 parts of stearic acid, 3 parts of saturated hydrocarbonsoftener, 2.5 parts of sulfur, 0.5 part of Product A, and 1.5 parts ofN-nitroso diphenylamine, a retarder particularly effective withsulfenamide accelerators. The stock was cured for 45 minutes in a pressat 144 C. and compared with a similarly prepared and cured stock butcontaining, in place of Product A, an equal weight of a commercialsulfenamide delayed action accelerator. The test results obtained wereas follows:

TABLE 111 Commercial Product Benzothi- A azolesulfenamlde Modulus ofElasticity in lbs/in. at 300% Elongation 2,243 2,206 Tensile at break inlbs/ink. 4,100 4,063 Mooney scorch at 121 0..-- 74 43 Products D and Ewere tested in similar formulations containing N-nitroscdiphenylamineexcept that the stocks contained only 1.0 part of N-nitrosodiphenylamineand While the invention has been illustrated by use of elemental sulfuras the vulcanizing agent, other vulcanizing systems are applicable.Various N,N-thioamines are known to be vulcanizing agents, as forexample N,N-dithiobis morpholine, and may be used in the practice of theinvention. In general, any sulfur vulcanizing agent is suitable whetherin the form of elemental sulfur or selenium orin the form'of a sulfurcompound which releases sulfur at vulcanizing temperature. The sulfurlevel can be varied to achieve particular objectives. The acceleratorsmay be used alone or in admixture with other accelerators, as forexample diphenyl guanidine, usually in amounts within the range of 0.1-5.0%

Other sulfur vulcanizable diene rubbers can be used in the practice ofthe invention. These include styrenebutadiene copolyrner rubbers,polybutadiene, isobutylene polymerized in the presence of a small amountof a diene hydrocarbon (butyl rubber) and the like.

It is intended to cover all changes and modifications of the examples ofthe invention herein chosen for purposes of disclosure which do notconstitute departures from the spirit and scope of the invention.

This application is a continuation-in-part of application Serial No.631,070, filed December 28, 1956, now US. Patent 2,875,208, grantedFebruary 24, 1959.

What is claimed is:

1. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of a propynyl-Z-benzothiazolesulfenamide.

2. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of a sulfenamide having the structure x-s-N CH-CEGHwherein R represents an alkyl group containing not more than five carbonatoms and X represents an aryl thiazole radical the aryl radical ofwhich is selected from the benzene series.

3. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of a sulfenamide having the structure B x-s-NOIL-CECE wherein R represents a saturated hydrocarbon radical containingnot more than six carbon atoms and X reprecents an aryl thiazole radicalthe aryl radical of which is selected from the benzene series.

4. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of a sulfenamide having the structure X-S-N whereinR represents a branched chain lower alkyl group and X represents theZ-benzothiazole radical.

5. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of N-isopropyl-N- 2-propyny1)-2-benzothiazolesulfenamide.

6. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of 5 'chloro-N-isopropy1-N-( 2*propynyl) 2benzothiazolesulfenamide. a

7. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of N- isopropyl-4-methyl-N-(Z-propynyl) 2benzothiazolesulfenamide.

8. A process of vulcanizing rubber which comprises heating atvulcanizing temperature rubber having incorporated therein sulfur and anaccelerating amount of 6- ethoxy-N-isopropyl-N-(Z-propynyl) 2benzothiazolensulfenamide.

9. A rubber product vulcanized by the process of claim 1.

10. A vulcanizable rubber product having incorporated therein anaccelerating amount of N-isopropyl-N- (Z-pmpyuyl)-2-benzothiazolesulfenamide.

11. A vulcanizable rubber product having incorporated therein anaccelerating amount of S-chloro-N-isopropyl-- 2-propynyl)-2-benzothiazolesulfenamide.

12. A vulcanizable rubber product having incorporated therein anaccelerating amount of 6 ethoxy-N-isopropyl-N- 2-propynyl) -2-benzothiazolesulfenamide.

References Cited in the file of this patent UNITED STATES PATENTS2,560,021 Smith July 10, 1951 2,875,208 D'Amico Feb. 24, 1959 Disclaimer2,943,079. John J. DAmico, Nitao, W. V a. VULCANIZING RUBBER WITH Patentdated June 28, 1960. Disclaimer PROIYNYL SULFENAMIDES. filed May =20,1964, by the assignee, Monsanto Chemical Company.

Hereby enters this disclaimer to claims 1 and 9 of said patent.

[Ofiicial Gazette August 18,1964]

1. A PROCESS OF VULCANIZING RUBBER WHICH COMPRISES HEATING ATVULCANIZING TEMPERATURE RUBBER HAVING INCORPORATED THEREIN SULFUR AND ANACCELERATING AMOUNT OF A PROPYNYL-2-BENZOTHIAZOLESULFENAMIDE.